Temperature compensating means for closed hydraulic system



June 15, 1965 CHAMBERS 3,189,051

TEMPERATURE COMPENSATING MEANS FOR CLOSED HYDRAULIC SYSTEM Filed May 4, 1962 INVENTOR.

Ea er) E Cfiambera v BY United States Patent TEMPERATURE COMPENSATDJG MEANS FOR CLOSED HYDRAULIC SYSTElt I Robert B. Chambers, Lander, Wyo., assignor to Belt- Scales Corporation, Salt Lake City, Utah, a corporation of Nevada Filed May 4, 1962, Ser. No. 192,444

8Clairns. (Cl. 13830) 7 The present invention relates to an apparatus or means to be used to compensate for the change in volume of liquid caused by variation in temperature when liquid in a closed hydraulic system is used for control or actuation purposes.

In many cases the unique qualities of a hydraulic medium make it very desirable for various applications,

.perature change compensating apparatus.

ice

in the direction'indicated by the arrowsas shown in FIGURE 1. a

As shown on the drawings:

The reference numeral 10 indicates generally a tem- The apparatus 10 includes a closed hydraulic system indicated generally at 11. A tube 12, a reservoir 13 and a small bellows which in elfect comprise a flexible movable wall, as v identified at 14, together comprise the closed hydraulic system. These components are so constructed and placed that they are acted upon by the same temperature variations as the main hydraulic system, to hereafter. be discussed in further detail.

It will be noted that the apparatus 10 is provided with frame means indicated generally at 15 including a frame base 16, upright frame members 17, 18 and 19, and an overhead frame member 20. The reservoir 13 carries the bellows 14 and the reservoir 13 is supported on the base frame member 16. The bellows 14 is provided with a bellows stem 21 that is connected with a slidable bar 22 by means of a connecting pin 23. A slide bar guide and support means 24 is provided for supporting the liquid in the primary hydraulic system to be varied through variations of temperature and enabling the hydraulic liquid in the primary hydraulic system to be maintained at a constant pressure.

An important object of this invention is to provide means for compensating for change in volume of liquid caused by variation in temperature when liquid in a closed hydraulic system is used for control or actuation purposes.

Yet another object of this invention is to provide a temperature change compensating apparatus which is self-operated and requires little or no adjustment after it has once been installed and made a part of a primary hydraulic system.

A still further important object of this invention is to provide a temperature change compensating apparatus .having relatively simple component parts which can be readily manufactured, assembled together and replaced, when necessary. 7

Another object of this invention is to provide a means for using a hydraulic element in a structure of other material or materials and by altering the volume of the hydraulic element by the compensator, counter the effects of temperature change upon the materials of the structure, thereby maintaining the structure in a relative constant position.

According to important features of the present invention, my temperature change compensating apparatus includes a pair of bellows, one for attachment with a primary hydraulic system and anotherfor attachment with a closed hydraulic system, the bellows connected with the closed hydraulic system having a reciprocating arm which moves as a result of temperature variations, and means mounted on the slidable arm connected with the first bellows for varying the volumetric capacity of the first bellows in accordance with the movement of the slidable arm.

Other objects and features of this invention will more fully become apparent in view of the following detailed description taken in conjunction with the accompanying drawings illustrating a single embodiment and in which:

FIGURE 1 is a side elevation, with certain details shown in section, of a temperature change compensating apparatus; and

FIGURE 2 is a vertical section with parts shown in elevation, taken substantially on the line IIII. looking slidable bar 22 as it is reciprocated between the upright frame members17 and 18. The slide bar support means 24 includes a roller 25 carried on roller stub shafts 25a, 25a which in turn are supported on roller support block 25b. a

The slidable bar 22 has a reduced end 22a which is journaled on the vertical or upright frame member 19 as indicated at 19a. The vertical or upright frame member 19 also acts as a base for spring 25 which acts upon bar shoulder 26- to force the slidable bar in a direction toward the bellows 14.

V The slidable arm 22 has an inclined roller supporting surface 27, which in the illustrated form of the invention, is formed as a part of a roller support bar 28. The slidable bar 22 has a pin 29 that is engaged within recess 30 on the roller support bar 28 at one of its ends. The roller support bar is further provided with means in the form of a screw 30 which is threaded through the roller support bar 28 and engaged for support on the slidable bar 22. In order to vary theangle of inclination of the inclined surface 27, the screw 30 may be turned in the direction and to the extent desired.

The overhead frame member 20carries a large bellows which in eifect comprises aflexibly movable wall, as identified at 31. The bellows 31 is a part of a primary hydraulic system indicated at 32. The bellows 31 is supported at its bottom side on a pivotal bellows support arm 33. To this end, the upright frame member 18 is provided with an extension 34 and a pivot pin 35 is provided for securing the pivotal arm 33 with the extens'ion 34. -:The bellows 31 has a lower end 36 provided with a pair of roller guides 3737 carrying roller 38 on pivot pin 39. The roller 38 is supported on the inclined surface 27.

The upper end of the bellows is firmly positioned on the overhead frame member 20 and includes a tube 40 which is externally threaded at 4-1. The threads 41 are engaged with an internally threaded bushing 42. The bushing 42 is locked with the overhead frame member 20 by means of a key 43 extended through an opening 44a in a surrounding collar'44 and extended into sleeve opening 42a. It will be appreciated that the volumetric capacity of the bellows 31 can be manually adjusted by rotating the collar 44, which causes the externally threaded tube 49 to move up and down inaccordance with the direction of rotation of the collar 44. 7

Operation 7 The apparatus 10 may be placed into operation by filling the closed hydraulic system 11 with the proper amount of hydraulic liquid and by permanently sealing the tube 12. The tube 12 may be sealed by inserting a plug 46 with an O-ring 47 fitted to it whereupon the tube 12 is crimped to secure the plug in position. While the closed hydraulic system 11 is being filled with liquid, the spring 25 must be compressed so that the bellows 14 will not be collapsed. After the tube 12 has been crimped, the spring 25 is released so that it forces the slidable bar 22 toward the bellows 14. The liquid in the closed hydraulic system 11 holds the bellows 14 from collapsing. As the bellows expands and contracts according to temperature changes, it will be appreciated that the bar 22 is caused to move back and forth depending on whether the hydraulic liquid in the closed system 12 expands or contracts.

-Where the temperature changes, the bar 22 is moved along withthe inclined surface 27. Since the roller 38 rests on the inclined surface, it will be caused to move up and down with the bellows 31 and cause a proportional change in volume'of fluid in the bellows 31.

As an example, a rise in temperature causes the liquid in the closed hydraulic system 12 to expand. forcing the bar 22 in a direction away from the upright 17 which compresses the spring 25' and allows the lower end 36 of the bellows 3-1 to drop whereby the volume of the bellows 31 is increased to compensate for the expansion of liquid in the primary hydraulic system 32 permitting a constant pressure to be maintained in the primaryhydraulic system. A fall in temperature causes the apparatus to operate in a reverse manner.

It is necessary for the spring 25' to exert a sufiieient force to overcome the force exerted by the roller 38 on the inclined surface 27 so that the position of the bar 22 is entirely controlled by the volume of liquid in the closed hydraulic system 12.

Of course, the arrangements of components as illustrated is only one of many that may be used to obtain the results of the present invention. As a further example, a combination of levers and pivots, as well as diaphragms or other resilient means can replace the bellows and springs to obtain results by the same principle.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

1 claim as my invention:

:1. In a temperature change compensating apparatus for a primary hydraulic system including frame means,

a first resilient means for attachment with the primary hydraulic system and mounted on said frame means, a closed hydraulic system including a second resilient means mounted on said frame means,

a slidable bar connected with said second resilient means,

means connected to said slidable bar urging it toward said second resilient means, and

means mounted on said slidable arm for moving said first resilient means for varying the volumetric capacity of the primary hydraulic system to maintain a constant pressure in the primary hydraulic system as said slidable arm is reciprocated as a result of temperature variations causing variations in the volumetric capacity of said second resilient means.

2. In a temperature change compensating apparatus for a primary hydraulic system including frame means,

a first bellows for attachment with the primary hydraulic system and mounted on said, frame means,

a closed hydraulic system including a second bellows mounted on said frame means and having a bellows stem projecting therefrom,

a slidable bar connected with said bellows stem,

resilient means connected to said slidable bar urging said bellows stem toward said second bellows,

means mounted on said slidable arm for moving said first bellows as said bellows stem and said slidable arm are reciprocated as a result of temperature variations causing variations in the volumetric capacity of said second bellows for varying the volumetric capacity of the first bellows to maintain a constant pressure in the primary hydraulic system, and

means for manually varying the volumetric capacity of said first bellows.

3. In a temperature change compensating apparatus for a primary hydraulic system including frame means including upright and overhead frame members,

a first bellows for attachment with the primary hydraulic system and mounted on said overhead frame member and being mounted on a roller on its underside,

a closed hydraulic system including a second bellows mounted on said frame means and having a bellows stem projecting therefrom,

a slidable bar connected with said bellows stem,

resilient means connected to said slidable bar urging said bellows stem toward said second bellows, and

means mounted on said slidable arm including an inclined roller supporting surface engaged with said roller for moving said first bellows up and down for varying the volumetric capacity of the first bellows to maintain a constant pressure in the primary hydraulic system as said bellows stem and said slidable arm as well as said inclined surface are reciprocated as a result of temperature variations causing variations in the volumetric capacity of said second bellows.

4. In a temperature change compensating apparatus for a primary hydraulic system including frame means having upright and overhead frame members,

a first bellows for attachment with the primary hydraulic system and mounted on said overhead frame member and being supported at its lower end on an arm pivoted at one end on said frame upright member,

said arm being carried by a roller on its underside,

a closed hydraulic system including a second bellows mounted on said frame means and having a bellows stern projecting therefrom,

a slidable bar connected with said bellows stem,

resilient means connected to said slidable bar urging said bellows stem toward said second bellows, and

means mounted on said slidable arm including an inclined roller supporting surface supporting said roller for moving said first bellows up and down for varying the volumetric capacity of the first bellows to maintain a constant pressure in the primary hydraulic system as said bellows stem and said slidable arm as well as said inclined surface are reciprocated as a result of temperature variations causing variations in the volumetric capacity of said second bellows.

5. In a temperature change compensating apparatus for a primary hydraulic system including I frame means having upright and overhead frame members,

a first bellows for attachment with the primary hydraulic system and mounted on said overhead frame member and being supported at its lower end on an arm pivoted at one end on said frame upright member,

said arm being carried by a roller on its underside,

a closed hydraulic system including a second bellows mounted on said frame means and having a bellows stem projecting therefrom,

a slidable bar connected with said bellows stem,

resilient means connected to said slidable .bar urging said bellows stern toward said second bellows,

means mounted on said slidable arm including an inclined roller supporting surface supporting said roller for moving said first bellows up and down for varying the volumetric capacity of the first bellows to maintain a constant pressure in the primary hydraulic system as said bellows stem and said slidable arm as Well as said inclined surface are reciprocated as a result of temperature variations causing variations in the volumetric capacity of said second bellows,

a roller support bar on said slidable bar having said inclined roller supporting surface along its side, and

means connected with said bar for adjusting the extent of inclination of said surface.

6. In a temperature change compensating apparatus for a primary hydraulic system including frame means,

a first bellows for attachment with the primary hydraulic system and mounted on said frame means,

a closed hydraulic system comprising a tank including a second bellows operatively connected at one end with said tank and mounted on said frame means and having a bellow stem projecting from an opposite end,

a slidable bar connected with said bellows stern,

resilient means connected to said slidable bar urging said bellows stern toward said second bellows, and

means mounted on said slidable arm for moving said first bellows for varying the volumetric capacity of the first bellows to maintain a constant pressure in the primary hydraulic system as said bellows stem and said slidable arm are reciprocated as a result of temperature variations causing variations in the volumetric capacity of said second bellows.

7. In a temperature change compensating apparatus for a primary hydraulic system including frame means having upright and overhead frame members,

a first bellows for connection with the primary hydraulic system having mounting means securing first bellows on said overhead frame member and with the first bellows being supported at its lower end on an arm pivoted at one end on said frame upright member,

said arm being carried by a roller on its underside,

a closed hydraulic system including "a second bellows mounted on said frame means and having a bellows stem projecting therefrom,

a slidable bar connected with said bellows stem,

resilient means connected to said slidable bar urging said bellows stern toward said second bellows, means mounted on said slidable arm including an inclined roller supporting surface supporting said roller for moving said first bellows up and down for varying the volumetric capacity of the first bellows to maintain a constant pressure in the primary hydraulic system as said bellows stem and said slidable arm as Well as said inclined surface are reciprocatcd as a result of temperature variations causing variations in the volumetric capacity of said second bellows, and

a roller support bar having said inclined roller supporting surface along its side,

said mounting means having a manual adjustment control for moving the first bellows up and down to vary its volumetric capacity.

8. In a temperature change compensating apparatus for a primary fluid system,

frame means,

a first bellows disposed in an upright position and connected at an upper end with the primary hydraulic system and being mounted on said frame means,

an arm positioned beneath and supporting said first bellows at its lower end,

said arm being carried by a bearing,

a closed hydraulic system comprising a fluid tank including a second bellows joined at one end with said tank and having a bellows stem projecting from an opposite end,

a slidable bar connected with said bellows stem,

resilient means connected to said slidable bar urging said bellows stem toward said second bellows, and

cam means mounted on said slidable arm beneath said first bellows including an inclined roller supporting surface supporting said bearing for moving said first bellows up and down for varying the volumetric capacity of the first bellows to maintain a constant pressure in the primary hydraulic system as said bellows stem and said slidable arm as well as said inclined surface are reciprocated as a result of temperature variations causing variations in the volumetric capacity of said second bellows.

References Cited by the Examiner UNITED STATES PATENTS 1,218,771 3/17 Hoeschen '74-11() 1,751,646 3/30 Nieman 74110 1,830,869 11/31 Charles l3830 2,367,707 1/45 Amery 138-30 X 2,847,035 8/58 Peters 138-30 3,085,595 4/63 Armstrong et a1. 92-1 5O EDWARD V. BENHAM, Primary Examiner.

LEWIS I. LENNY, Examiner. 

1. IN A TEMPERATURE CHANGE COMPENSATING APPARATUS FOR A PRIMARY HYDRAULIC SYSTEM INCLUDING FRAME MEANS, A FIRST RESILIENT MEANS FOR ATTACHMENT WITH THE PRIMARY HYDRAULIC SYSTEM AND MOUNTED ON SAID FRAME MEANS, A CLOSED HYDRAULIC SYSTEM INCLUDING A SECOND RESILIENT MEANS MOUNTED ON SAID FRAME MEANS, A SLIDABLE BAR CONNECTED WITH SAID SECOND RESILIENT MEANS, MEANS CONNECTED TO SAID SLIDABLE BAR URGING IT TOWARD SAID SECOND RESILIENT MEANS, AND MEANS MOUNTED ON SAID SLIDABLE ARM FOR MOVING SAID FIRST RESILIENT MEANS FOR VARYING THE VOLUMETRIC CAPACITY OF THE PRIMARY HYDRAULIC SYSTEM TO MAINTAIN A CONSTANT PRESSURE IN THE PRIMARY HYDRAULIC SYSTEM AS SAID SLIDABLE ARM IS RECIPROCATED AS A RESULT OF TEMPERATURE CAPACITY OF SAID SECOND RESILIENT MEANS. 